Research on Mechanism and Control of In-situ Steering for Distributed Drive Electric Vehicles
Distributed electric drive vehicles can improve vehicle mobility through in-situ steering capabilities.All four wheels of the vehicle are experiencing slipping,creating a situation where the vehicle body is prone to drifting or even losing control.To achieve stable and accurate in-situ steering control,this article analyzed the dynamic mechanism of in-situ steering and proposed a control strategy that coordinates yaw and slip rates.This study designed a road adhesion estimation algorithm based on longitudinal dynamics to complete the evaluation of road conditions before in-situ steering.It adopted a hierarchical control architecture.The upper-layer controller coordinated the torque control strategy based on the vehicle state,and the lower-layer control designed a yaw rate decision-making framework.The nominal yaw rate of the original steering was determined by considering the throttle opening,and the four-wheel-drive torque was calculated using a single-neuron adaptive PID(SNAPID)control algorithm.This algorithm,based on a quadratic performance index,was employed to achieve tracking control of the yaw speed.The expected slip rate of the four wheels was obtained by introducing fuzzy logic reasoning,and the drive torque adjustment was calculated using the PID algorithm and was combined with the yaw rate torque control to suppress the deviation of the steering center.Simulation tests and real vehicle tests show that:when the adhesion coefficient is constant,the tire turning in a steady state is regarded as a rigid body,and the side slip angle and the lateral reaction force on the ground are unchanged,the test results are consistent with the inferred steering dynamics.The test results confirmed that the yaw rate tracking control algorithm exhibits excellent tracking performance and robustness across various attachments.In comparison to PID,the algorithm demonstrated a 46%increase in response speed,a 24.0%reduction in maximum overshoot,and a shortened average adjustment time by 1.3 seconds.The average steady-state errors were consistently maintained at 0.01(°)·s-1.The control of yaw rate and slip rate contributed to a reduction in horizontal and vertical coordinate offsets by 2.94 meters and 1.69 meters,effectively mitigating steering center offset.
automotive engineeringin-situ steeringcoordinated controldrive electric vehiclessingle-neuron adaptive PID